Mechanical & Fluid Systems

Pulse-Echo Probe Mounting Fixture for Blind Alignment on Pipes

This technology enables an effective, real-time, in-service health monitoring system for steam pipes.

The probe and its mounting fixture are critical parts of the health monitoring of steam pipes. A high-temperature, piezoelectric transducer generates and receives ultrasonic waves, and the probe has to transmit the wave normal to the pipe surface. The mounting fixture is designed to allow for alignment of the probe even without a reference reflection, and thus enables blind alignment. In order to allow aligning of the probe normal to the surface of potential water condensation, and to secure intimate contact to the pipe surface, a novel mounting fixture was conceived and developed.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Mountings

Passive Mechanism for Maintaining Tension at a Spool to Within a Given Window

This innovation can be used with a vehicle, crane, winch, or boat, or for rock climbing, water skiing, and parasailing.

During any winding or unwinding action, a tether may experience unexpected changes in tension. For example, the load being wound could become stuck and stop moving, causing the tension in the line to suddenly become extremely high. Alternatively, the load could slip, causing a lack of tension, or slack, in the line. Both of these scenarios can be harmful to neatly winding a spool in a tightly packed pattern. Excessive tension can cause one layer of line to become lodged in a layer below it and jammed. Too low of tension can cause the line on the spool to partially unravel and cause disorganized spooling. A novel mechanism utilizes the tension in the line and springs to hold a pulley between friction pads and a ratcheting mechanism to keep the tension at the spool within a particular window.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Wiring, Wiring, Materials handling, Packaging, Fibers

Miniature, Multi-Functional, Self-Braking Vehicle

This vehicle is actuated by piezoelectric stacks through the fuselage walls.

NASA’s Jet Propulsion Laboratory, Pasadena, California

A novel, miniature, low-mass vehicle has been created that is driven by piezoelectric stacks and a resonance structure. Preliminary tests on similar mechanisms that are used to transmit electrical power across the wall showed efficiencies of the order of 90%. The transmitted mechanical power, and signals through metallic walls using the direct and indirect piezoelectric effects in similar motors, is of the order of 50%. The transmitted power is generated inside the vehicle body, and the mechanism is applicable to any robotic system that may require an ambulation of locomotion mechanism such as a rover, a miniature vehicle, a crawler, or a flying device.

Posted in: Briefs, TSP, Mechanical Components, Power electronics, Power electronics, On-board energy sources, Robotics, Nanotechnology

Zero-Gravity Mobile Robot Using ON/OFF Adhesive Pads and Inchworm Mechanism

The robot has applications in military reconnaissance, and as a commercial toy.

NASA’s Jet Propulsion Laboratory, Pasadena, California

Inspection of the International Space Station and other manmade objects in space is difficult because of the microgravity environment. Robots are a promising approach to accomplish these inspection tasks and later repairs, but must be able to maneuver across the surfaces. Because there is no gravity, the robot is at high risk of floating away, necessitating grippers that can adhere to the surface and resist the forces and torques of inspecting and moving on the structure.

Posted in: Briefs, Mechanical Components, Terrain, Robotics, Spacecraft

Aluminum Gas Tungsten Arc Orbital Tube Welding

Orbital tube butt welding could be performed on aluminum tubes.

NASA’s Jet Propulsion Laboratory, Pasadena, California

JPL has been hand-welding aluminum tubing for decades in support of flight programs and ground support equipment, including thermal plates and shrouds. This hand-welding process is time-consuming, cumbersome, difficult, and unreliable in terms of repeatability and success, which leads to leaks, rework, and cost increase. Socket-style meltdown welds are difficult to inspect via traditional nondestructive evaluation (NDE) methods (radiography) since by design, there is always an inherent highstress point in the joint.

Posted in: Briefs, TSP, Mechanical Components, Welding, Aluminum

Precise Direct Control of Pressure or Vacuum Using a Digitally Controlled Actuator

A closed/semi-open pressure or vacuum system uses an electric screw mechanical actuator that can be digitally controlled and monitored, and which receives feedback directly from an external or internal source. This innovation can adjust for media temperature changes, expansion, and contraction in a constant volume and pressure system. This is done by extending or retracting a leak-free, high-pressure, or vacuum-sealed piston that is controlling pressure or vacuum.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Sensors and actuators, Sensors and actuators, Pistons

Use of Eccentric Bushings to Precision-Locate Multiple Parts on a Large Mating Structure

Lyndon B. Johnson Space Center, Houston, Texas

Cups/cones are being used to provide a shear load transfer capability on a large separation interface that uses multiple discreet retention and release (R&R) devices (such as frangible nuts, separation nuts, separation bolts, etc.). To both provide good shear load-sharing among all R&Rs and to prevent relative motion between the mating structures, the cups/cones must be designed with minimal (and sometimes zero) radial clearance. This tight fit requires that the cup and the cone on the mating structures are precisely located to each other.

Posted in: Briefs, Mechanical Components, Fastening, Parts

Effective Packing of Large Panels via Scrolling and Origami Folding

The packing mechanism employs an origami configuration that may have sport and military applications.

NASA’s Jet Propulsion Laboratory, Pasadena, California

There is a need for large mirrors that can be launched to various bodies in the solar system in a packed form and unfolded to provide the required dimensions. The solution to the need for foldable panels that can be made as mirrors or other structures including antennas, etc. has been conceived using an origami configuration that is folded in two dimensions. The foldable panel configuration, if made as a mirror, allows supporting rover operation in craters and caves that are shadowed and inaccessible to direct sunlight. The benefits of its use include providing light to the solar cells of the rover, providing a heating source using sunlight, and illuminating the area of operation where the rover is located.

Posted in: Briefs, TSP, Mechanical Components, Antennas, Antennas, Solar energy, Spacecraft

Six-Degree-of-Freedom Control With Only Eight Thrusters

Even as few as eight thrusters can provide six-degree-of-freedom control of a spacecraft and do so without undesired coupling between torque and translational force generation functions.

NASA’s Jet Propulsion Laboratory, Pasadena, California

Typical spacecraft thruster configurations are often unable to provide full six-degree-of-freedom control and may have unwanted interaction between their attitude control and trajectory control functions, have undesirably high instantaneous electrical power demands, and use more thrusters than desirable. These last two potential problems gain increased significance if a spacecraft is required to have especially small size and mass, and have very low cost.

Posted in: Briefs, TSP, Mechanical Components, Attitude control, Attitude control, Spacecraft

Irreversible Entropy Production Rate in High-Pressure Turbulent Reactive Flows

NASA’s Jet Propulsion Laboratory, Pasadena, California

To model high-pressure reactive flows, the most promising methodology is large eddy simulation (LES) in which one solves the large scales of the problem and models the small scales. There is currently no guidance as to the relative importance of small scales originating from different phenomena.

Posted in: Briefs, Mechanical Components, Simulation and modeling

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